Technical Field
The present invention relates to an adhesive layer equipped film-like pressure-sensitive sensor (i.e. “film-like pressure-sensitive sensor having an adhesive layer”), a touch pad, a touch-input function equipped protective panel (i.e. “protective panel having a touch-input function”), and an electronic device, all using the sensor.
Background Art
In recent years, there has been conspicuously increasing popularity of an electronic device 100 having a touch-input function such as a smart phone, a tablet type multi-function terminal device (see FIG. 14). With such electronic devices having a touch-input function, a user can input information in a readily intuitive manner by touching an image displayed on a display unit such as a liquid crystal display, with his/her finger, a pen or the like or placing the finger or the like near the image, while viewing the image for reference.
FIG. 15 is a section view showing a general configuration of a touch-input face and its vicinity included in the electronic device 100 having a touch-input function. As shown in FIG. 15, the electronic device 100 having a touch-input function includes a display unit 101, a protective panel 102 having a touch-input function, the protective panel 102 having a picture-frame-shaped ornamental pattern 102a and covering the display unit 101, and a casing 103 formed concave (a panel fit-in portion 105) to provide a level difference for allowing fit-in therein of the touch-input function equipped protective panel 102 from the outside, and having, in its bottom face, a cavity 105a for the display unit 101 and a frame-shaped support portion 105b for supporting a peripheral edge portion of the touch-input function equipped protective panel 102.
The above-described touch-input function equipped protective panel 102 protects the display screen of the display unit 101 and also allows touch-input. Conventionally, there has been employed a touch panel configured to detect coordinates of a position(s) touched by an operator. For multi-function terminal device such as a smart phone, a tablet, a capacitive touch panel allowing multiple touch inputs (detection of two or more multiple points) is mainly used. In electronic devices with touch-input function for other applications, other types of touch panel such as resistive film type, etc. is also used. Further, as shown in FIG. 15, since the touch-input function equipped protective panel 102 is fitted to the casing 103 from its outside, the protective panel 102 is provided with the picture-frame-shaped ornamental pattern 102a for hiding in order to deprive visibility of “inconvenient” portions (wiring portion of the touch panel, wiring portion of the display unit, etc.) (see FIG. 14). Further, the protective panel 102 is firmly supported to the support portion 105b of the casing 103 by a frame-shaped double-sided tape strip (adhesive layer) 8 provided in the rear face peripheral edge portion.
However, the touch-input function equipped protective panel 102 described above detects only coordinates of a position(s) touched by an operator, the panel 102 being incapable of detecting a pressing force of the operator's touch.
Then, it is conceivable to configure a touch-input function equipped protective panel such that on an entire rear face of the touch panel having a picture-frame-shaped ornamental pattern, a film-like pressure-sensitive sensor is affixed for detecting a pressing force of an operator's touch. As such film-like pressure-sensitive sensor as above, there is well-known, as disclosed in Patent Document 1, one configured such that between a pair of opposing transparent substrates, there are provided a transparent rectangular piezoelectric film having a pressure-sensitive layer having piezoelectric property, a transparent reference potential electrode formed on an entire front face of the piezoelectric film, and a transparent detection electrode formed on an entire rear face of the piezoelectric film (see Patent Document 1). Incidentally, in the case of the configuration with the addition of the film-like pressure-sensitive sensor thereto, the frame-shaped double-sided tape strip (adhesive layer) for fixing the touch-input function equipped protective panel is to be provided in a rear face peripheral edge portion of this film-like pressure-sensitive sensor.